Dark Current Reduction for Back Side Illuminated Image Sensor

ABSTRACT

A method of fabricating a semiconductor image sensor device is disclosed. A plurality of radiation-sensing regions is formed in a substrate. The radiation-sensing regions are formed in a non-scribe-line region of the image sensor device. An opening is formed in a scribe-line region of the image sensor device by etching the substrate in the scribe-line region. A portion of the substrate remains in the scribe-line region after the etching. The opening is then filled with an organic material.

PRIORITY DATA

The present application is a divisional patent application of U.S.patent application Ser. No. 13/305,069, filed on Nov. 28, 2011, thedisclosure of which is hereby incorporated by reference in its entirety.

BACKGROUND

Semiconductor image sensors are used to sense radiation such as light.Complementary metal-oxide-semiconductor (CMOS) image sensors (CIS) andcharge-coupled device (CCD) sensors are widely used in variousapplications such as digital still camera or mobile phone cameraapplications. These devices utilize an array of pixels in a substrate,including photodiodes and transistors, that can absorb radiationprojected toward the substrate and convert the sensed radiation intoelectrical signals.

A back side illuminated (BSI) image sensor device is one type of imagesensor device. These BSI image sensor devices are operable to detectlight projected from the backside. The BSI image sensor devices includecolor filters for filtering a specific wavelength band of the incominglight, which corresponds to a color in a color spectrum. However,conventional methods of forming color filters for BSI image sensordevices have been prone to suffer from thermal expansion issues,particular in a scribe line region of the BSI image sensor device. Suchthermal expansion may cause lateral stress to a photo-sensitive regionof the image sensor and degrade dark current performance of the imagesensor.

Therefore, while existing semiconductor image sensors have beengenerally adequate for their intended purposes, they are not entirelysatisfactory in every aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1 is a flowchart illustrating a method for fabricating an imagesensor device according to various aspects of the present disclosure.

FIGS. 2-9 are diagrammatic fragmentary cross-sectional side views of animage sensor device at various stages of fabrication in accordance withvarious aspects of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific examples of components and arrangements aredescribed below to simplify the present disclosure. These are, ofcourse, merely examples and are not intended to be limiting. Moreover,the formation of a first feature over or on a second feature in thedescription that follows may include embodiments in which the first andsecond features are formed in direct contact, and may also includeembodiments in which additional features may be formed interposing thefirst and second features, such that the first and second features maynot be in direct contact. Various features may be arbitrarily drawn indifferent scales for the sake of simplicity and clarity.

Illustrated in FIG. 1 is a flowchart of a method 10 for fabricating asemiconductor image sensor device according to various aspects of thepresent disclosure. Referring to FIG. 1, the method 10 includes block 15in which a plurality of radiation-sensing regions is formed in asubstrate. The radiation-sensing regions are formed in a non-scribe-lineregion of the image sensor device. The method 10 includes block 20 inwhich an opening is formed in a scribe-line region of the image sensordevice. The opening is formed etching the substrate in the scribe-lineregion. A portion of the substrate remains in the scribe-line regionafter the etching. The method 10 includes block 25 in which the openingis filled with an organic material. It is understood that additionalprocessing steps may be performed before, during, or after the method 10of FIG. 1. But for the sake of simplicity, these additional processingsteps are not discussed in detail herein.

FIGS. 2 to 9 are diagrammatic fragmentary sectional side views ofvarious embodiments of an apparatus that is a back side illuminated(BSI) image sensor device 30 at various stages of fabrication accordingto aspects of the method 10 of FIG. 1. The image sensor device 30includes an array or grid of pixels for sensing and recording anintensity of radiation (such as light) directed toward a back-side ofthe image sensor device 30. The image sensor device 30 may include acharge-coupled device (CCD), complimentary metal oxide semiconductor(CMOS) image sensor (CIS), an active-pixel sensor (APS), or apassive-pixel sensor. The image sensor device 30 further includesadditional circuitry and input/outputs that are provided adjacent to thegrid of pixels for providing an operation environment for the pixels andfor supporting external communication with the pixels. It is understoodthat FIGS. 2 to 9 have been simplified for a better understanding of theinventive concepts of the present disclosure and may not be drawn toscale.

With reference to FIG. 2, the image sensor device 30 includes asubstrate 40, hereinafter referred to as a device substrate. The devicesubstrate 40 is a silicon substrate doped with a p-type dopant such asBoron (for example a p-type substrate). Alternatively, the devicesubstrate 40 could be another suitable semiconductor material. Forexample, the device substrate 40 may be a silicon substrate that isdoped with an n-type dopant such as Phosphorous or Arsenic (an n-typesubstrate). The device substrate 40 could include other elementarysemiconductors such as germanium and diamond. The device substrate 40could optionally include a compound semiconductor and/or an alloysemiconductor. Further, the device substrate 40 could include anepitaxial layer (epi layer), may be strained for performanceenhancement, and may include a silicon-on-insulator (SOI) structure.

Referring back to FIG. 2, the device substrate 40 has a front side (alsoreferred to as a front surface) 50 and a back side (also referred to asa back surface) 60. For a BSI image sensor device such as the imagesensor device 30, radiation is projected from the back side 60 andenters the substrate 40 through the back surface.

A plurality of dielectric trench isolation (STI) structures 65 is formedin the substrate 40. In some embodiments, the STI structures 65 areformed by the following process steps: etching openings into thesubstrate 40 from the front side 50; filling the openings with adielectric material such as silicon oxide, silicon nitride, siliconoxynitride, a low-k material, or another suitable dielectric material;and thereafter performing a polishing process—for example a chemicalmechanical polishing (CMP) process—to planarize the surface of thedielectric material filling the openings. In some embodiments, deeptrench isolation (DTI) structures may be formed. The formation processesfor the DTI structures may be similar to the STI structures 65, thoughthe DTI structures are formed to have greater depths than the STIstructures 65. In certain embodiments, doped isolation structures mayalso be formed. These doped isolation structures may be formed by one ormore ion implantation processes. The doped isolation structures may beformed to replace or to supplement the STI or DTI structures.

A plurality of pixels is formed in the substrate 40. The pixels containradiation-sensing doped regions 70. These radiation-sensing dopedregions 70 are formed by one or more ion implantation processes ordiffusion processes and are doped with a doping polarity opposite fromthat of the substrate 40 (or the doped region 140). Thus, in theembodiment illustrated, the pixels contain n-type doped regions. For aBSI image sensor device such as the image sensor device 30, the pixelsare operable to detect radiation, such as an incident light 75, that isprojected toward device substrate 40 from the back side 60.

In some embodiments, the pixels each include a photodiode. A deepimplant region may be formed below each photodiode in some embodiments.In other embodiments, the pixels may include pinned layer photodiodes,photogates, reset transistors, source follower transistors, and transfertransistors. The pixels may also be referred to as radiation-detectiondevices or light-sensors. The pixels may be varied from one another tohave different junction depths, thicknesses, widths, and so forth. Insome embodiments, each pair of adjacent or neighboring pixels areseparated from each other by a respective one of the isolationstructures (e.g., STI structures 65) discussed above. The isolationstructures 65 prevent or reduce cross-talk between the pixels.

The device substrate 40 also has an initial thickness 78, which ismeasured from the front side 50 to the back side 60. In someembodiments, the initial thickness 78 is in a range from about 100microns (um) to about 3000 um, for example between about 500 um andabout 1000 um.

Referring now to FIG. 3, an interconnect structure 80 is formed over thefront side 50 of the device substrate 40. The interconnect structure 80includes a plurality of patterned dielectric layers and conductivelayers that provide interconnections (e.g., wiring) between the variousdoped features, circuitry, and input/output of the image sensor device30. The interconnect structure 80 includes an interlayer dielectric(ILD) and a multilayer interconnect (MLI) structure. The MLI structureincludes contacts, vias and metal lines. For purposes of illustration, aplurality of conductive lines 90 and vias/contacts 95 are shown in FIG.3, it being understood that the conductive lines 90 and vias/contacts 95illustrated are merely examples, and the actual positioning andconfiguration of the conductive lines 90 and vias/contacts 95 may varydepending on design needs and manufacturing concerns.

The MLI structure may include conductive materials such as aluminum,aluminum/silicon/copper alloy, titanium, titanium nitride, tungsten,polysilicon, metal silicide, or combinations thereof, being referred toas aluminum interconnects. Aluminum interconnects may be formed by aprocess including physical vapor deposition (PVD) (or sputtering),chemical vapor deposition (CVD), atomic layer deposition (ALD), orcombinations thereof. Other manufacturing techniques to form thealuminum interconnect may include photolithography processing andetching to pattern the conductive materials for vertical connection (forexample, vias/contacts 95) and horizontal connection (for example,conductive lines 90). Alternatively, a copper multilayer interconnectmay be used to form the metal patterns. The copper interconnectstructure may include copper, copper alloy, titanium, titanium nitride,tantalum, tantalum nitride, tungsten, polysilicon, metal silicide, orcombinations thereof. The copper interconnect structure may be formed bya technique including CVD, sputtering, plating, or other suitableprocesses.

Still referring to FIG. 3, a buffer layer 100 is formed on theinterconnect structure 80. In the present embodiment, the buffer layer100 includes a dielectric material such as silicon oxide. Alternatively,the buffer layer 100 may optionally include silicon nitride. The bufferlayer 100 is formed by CVD, PVD, or other suitable techniques. Thebuffer layer 100 is planarized to form a smooth surface by a CMPprocess.

Thereafter, a carrier substrate 110 is bonded with the device substrate40 through the buffer layer 100, so that processing of the back side 60of the device substrate 40 can be performed. The carrier substrate 110in the present embodiment is similar to the substrate 40 and includes asilicon material. Alternatively, the carrier substrate 110 may include aglass substrate or another suitable material. The carrier substrate 110may be bonded to the device substrate 40 by molecular forces—a techniqueknown as direct bonding or optical fusion bonding—or by other bondingtechniques known in the art, such as metal diffusion or anodic bonding.

Referring back to FIG. 3, the buffer layer 100 provides electricalisolation between the device substrate 40 and the carrier substrate 110.The carrier substrate 110 provides protection for the various featuresformed on the front side 50 of the device substrate 40, such as thepixels formed therein. The carrier substrate 110 also providesmechanical strength and support for processing of the back side 60 ofthe device substrate 40 as discussed below. After bonding, the devicesubstrate 40 and the carrier substrate 110 may optionally be annealed toenhance bonding strength.

Still referring to FIG. 3, after the carrier substrate 110 is bonded, athinning process 120 is then performed to thin the device substrate 40from the backside 60. The thinning process 120 may include a mechanicalgrinding process and a chemical thinning process. A substantial amountof substrate material may be first removed from the device substrate 40during the mechanical grinding process. Afterwards, the chemicalthinning process may apply an etching chemical to the back side 60 ofthe device substrate 40 to further thin the device substrate 40 to athickness 130, which is on the order of a few microns. In someembodiments, the thickness 130 is greater than about 1 um but less thanabout 3 um. It is also understood that the particular thicknessesdisclosed in the present disclosure are mere examples and that otherthicknesses may be implemented depending on the type of application anddesign requirements of the image sensor device 30.

Referring now to FIG. 4, an anti-reflective coating (ARC) layer 150 isformed over the device substrate 40 from the back side 60. The ARC layer150 may be formed by a suitable deposition process, such as CVD, PVD,ALD, or combinations thereof. The ARC layer 100 may include a suitablematerial for reducing a reflection of radiation waves projected towardthe device substrate 40 from the back side 60. For example, the ARClayer 150 may contain nitrogen. The ARC layer 150 may also serve as anetching-stop layer. The ARC layer 150 has a thickness 160. In someembodiments, the thickness 160 is greater than about 200 Angstroms butless than about 1000 Angstroms.

Referring now to FIG. 5, an opening 180 is formed in the devicesubstrate 40. The opening 180 is formed in a scribe-line region 190 ofthe image sensor device 30. In general, the scribe line region is aregion that separates one semiconductor die from an adjacentsemiconductor die. The scribe line region is cut therethrough in a laterfabrication process to separate adjacent dies before the dies arepackaged and sold as integrated circuit chips. In comparison, theportions of the substrate 40 located on either side of the opening 180belong to pixel regions 200A and 200B of the image sensor device 30,since these portions of the substrate 40 contain radiation-sensitivepixels that can sense light. Thus, the portion of the image sensordevice 30 illustrated herein contains adjacent dies (whose pixel regionsare respectively shown herein as pixel regions 200A and 200B) that aredivided apart by the scribe-line region 190.

It is understood that in addition to the pixel regions 200A-200B and thescribe line region 190, the image sensor device 30 may also includeperiphery regions and bonding pad regions. The periphery region mayinclude digital devices, such as application-specific integrated circuit(ASIC) devices or system-on-chip (SOC) devices, or other referencepixels used to establish a baseline of an intensity of light for theimage sensor device 30. The bonding pad region is reserved for theformation of bonding pads, so that electrical connections between theimage sensor device 30 and external devices may be established. For thesake of simplicity, the details of these other regions of the imagesensor device 30 are not illustrated or described herein.

Referring back to FIG. 5, the opening 180 is formed by an etchingprocess 210. The etching process 210 includes a dry etching process insome embodiments. The etching process 210 is performed in a manner sothat the substrate 40 is not entirely removed in the scribe-line region190. Rather, a portion of the substrate 40A remains in the scribe-lineregion 190 (over the interconnect structure 80) even after the etchingprocess 200 is performed. This may be carried out by tuning certainetching parameters of the etching process 210, for example the etchingtime of the etching process 210. The substrate portion 40A has athickness 220. In some embodiments, the thickness 220 is greater thanabout 0 Angstroms but less than 4000 Angstroms. This substrate portion40A is contiguous and in direct physical contact with the portions ofthe substrate 40 in the pixel region 200s.

In this manner described above, the fabrication method according to thevarious aspects of the present disclosure “reserves” a substrate portion40A in the scribe-line region 190. This reserved portion of thesubstrate 40A can reduce dark current, as discussed in more detailbelow.

Referring now to FIG. 6, an anti-reflective coating (ARC) layer 230 isformed over the anti-reflective layer 150 in the pixel region 200 andover the substrate portion 40A in the scribe-line region 190. The ARClayer 230 is also formed on the sidewalls of the portions of thesubstrate 40 in the pixel region 200. The ARC layer 230 may be formed bya suitable deposition process, such as CVD, PVD, ALD, or combinationsthereof. The ARC layer 230 may include a suitable material for reducinga reflection of radiation waves projected toward the device substrate 40from the back side 60. For example, the ARC layer 230 may containnitrogen. In some embodiments, the ARC layers 150 and 230 have differentmaterial compositions. The ARC layer 230 has a thickness 240. In someembodiments, the thickness 240 is greater than about 200 Angstroms butless than about 3000 Angstroms.

Referring now to FIG. 7, an etching process 250 is performed in thescribe-line region 190 to “open” bonding pads 90A, which are a subset ofthe metal lines of the interconnect structure 80 in the scribe-lineregion 190. In other words, the etching process 250 removes the portionsof the ARC layers 230 and 150, and portions of the oxide materiallocated above the bonding pads 90A, so that the upper surfaces of thebonding pads 90A are exposed. The bonding pads 90A may be wire-bondedlater to establish electrical connections to the image sensor device 30.In some embodiments, the etching process 250 includes a dry etchingprocess.

Referring now to FIG. 8, an organic material 260 is formed to fill theopening 180 in the scribe-line region 190. The organic material 260 isformed besides the substrate 40 in the pixel region 200A and over theretained substrate portion 40A. However, the ARC layer 230 separates theorganic material 260 from the substrate 40 in the pixel region 200A andfrom the retained substrate portion 40A in the scribe-line region 190.

The organic material 260 is formed for purposes of creating a flatsurface for the formation of a color filter layer. In some embodiments,the organic material 260 may have the same material composition as thecolor filter layer and may be formed using the same processes that formthe color filter layer. The color filter layer may be formed on the backside 60 of the substrate 40 and over the ARC layer 150. The color filterlayer may contain a plurality of color filters that may be positionedsuch that the incoming radiation is directed thereon and therethrough.The color filters may include a dye-based (or pigment based) polymer orresin for filtering a specific wavelength band of the incomingradiation, which corresponds to a color spectrum (e.g., red, green, andblue). In alternative embodiments, the color filter layer may contain adifferent material than the organic material 260 and may be formedseparately (i.e., after) the organic material 260 is formed. For thesake of simplicity, the color filter layer is not specificallyillustrated herein.

After the formation of the color filter layer, a micro-lens layercontaining a plurality of micro-lenses is formed over the color filterlayer. The micro-lenses direct and focus the incoming radiation towardspecific radiation-sensing regions in the device substrate 40. Themicro-lenses may be positioned in various arrangements and have variousshapes depending on a refractive index of a material used for themicro-lens and distance from a sensor surface. The device substrate 40may also undergo an optional laser annealing process before the formingof the color filter layer or the micro-lens layer. It is understood thatboth the color filter layer and the micro-lenses are formed in the pixelregions 200A-200B of the image sensor device 30. For reasons ofsimplicity, the micro-lenses are not specifically illustrated hereineither.

Referring now to FIG. 9, a dicing process 280 is performed to thescribe-line region 190 so as to divide the image sensor device 30 intoseparate image sensor dies 300A and 300B. The dicing process 280 mayinclude a wafer sawing process in some embodiments. The wafer sawing maybe carried out using a blade, a laser beam, or another suitablemechanism. The dicing process 280 is performed in a manner so as to notdamage the image sensor device 30, for example the sidewalls of theimage sensor dies 300A and 300B.

The embodiments discussed above offer advantages over conventional imagesensor devices, for example advantages in dark current performances.However, it is understood that not all advantages are necessarilydiscussed herein, and other embodiments may offer different advantages,and that no particular advantage is required for all embodiments.

Dark current is a common type of image sensor defect and may be definedas the existence of pixel current when no actual illumination ispresent. In other words, the pixel “detects” light when it is notsupposed to. Dark current defects may be caused by stress inconventional image sensors. In more detail, the organic material fillingthe scribe-line region for conventional image sensors may have a highcoefficient of thermal expansion. Thus, as temperature rises, theorganic material expands in various directions, including in a lateraldirection. The lateral expansion of the organic material causes stressto the radiation-sensing devices of the pixel region. This stress mayinduce a bandgap of a charge carrier to be narrowed, which may result incarrier leakage and therefore give rise to dark current in conventionalimage sensors.

In comparison, the image sensor device 30 discussed above minimizes darkcurrent problems by not completely removing all portions of thesubstrate 40 in the scribe-line region 190. In more detail, a substrateportion 40A is retained when the scribe-line region 190 is etched. Theretained substrate portion 40A substantially reduces the amount ofstress (caused by organic material expansion) that is delivered to theradiation-sensing regions 70. One of the reasons why lateral stress isreduced is that the retained substrate portion 40A has the same materialcomposition as the substrate 40 and therefore does not have a thermalexpansion coefficient as high as that of the organic material 260.Hence, even as temperature rises, the substrate portion 40A causessubstantially no stress to the radiation-sensing region 70 nearby.Another reason is that the retained substrate portion 40A separates theradiation-sensing region 70 from the organic material 260 in thescribe-line region 190. Such separation effectively provides a “buffer”for stress caused by the thermal expansion of the organic material 190.Therefore, the amount of lateral stress experienced by theradiation-sensing region 70 may be reduced by the retained substrateportion 40A. For at least the reasons discussed above, due to theretained substrate portions 40A, the amount of lateral stress is reducedfor each image sensor die 300A-300B, and consequently dark currentperformance is improved.

It is understood that the thickness of the retained substrate portion40A in the scribe-line region may be correlated with the amount ofstress experienced by each of the image sensor dies 300A-300B.Typically, a thicker substrate portion 40A results in a smaller lateralstress for the image sensor dies 300A-300B. However, the substrateportion 40A cannot be too thick, because an excessive thickness mayprevent the bonding pads 90A from being “opened” as discussed above withreference to FIG. 7. In other words, if the retained substrate portion40A is too thick, then the etching process 250 may not be able tocompletely etch away the layers covering the bonding pads 90 to exposetheir surfaces.

On the other hand, if the substrate portion 40A is too thin, then it maynot sufficiently reduce lateral stress against the image sensor dies300A-300B. Thus, a careful tradeoff must be made. As discussed above,according to the various aspects of the present disclosure, a thicknessrange of between about ______ Angstroms and 4000 Angstroms has beenfound to be suitable for reducing lateral stress while not interferingwith bonding pad opening. It is understood, however, that otherthickness ranges for the retained substrate portion 40A may be used foralternative embodiments to accommodate different design requirements andmanufacturing concerns. For example, in embodiments where the bondingpad opening is not a concern, the thickness of the retained substrateportion 40A may be substantially greater than the range discussedherein, and possibly approaching the thickness of the substrate of theimage sensor dies.

Another advantage of the embodiments of the present disclosure is thatthey are fully compatible with existing manufacturing processes. Theimplementation of the embodiments of the present disclosure merelyinvolves tweaking existing fabrication processes. Therefore, noadditional manufacturing equipment is needed, nor are additionalfabrication steps performed. Consequently, the present disclosure doesnot increase fabrication costs or lengthen fabrication time.

It is understood that the sequence of the fabrication processesdescribed above is not intended to be limiting. Some of the layers ordevices may be formed according to different processing sequences inother embodiments than what is shown herein. Furthermore, some otherlayers may be formed but are not illustrated herein for the sake ofsimplicity.

One of the broader forms of the present disclosure involves an apparatusthat includes: a semiconductor image sensor device having anon-scribe-line region and a scribe-line region, the semiconductor imagesensor device including: a first substrate portion disposed in thenon-scribe-line region, wherein the first substrate portion contains adoped radiation-sensing region; and a second substrate portion disposedin the scribe-line region, wherein the second substrate portion has thesame material composition as the first substrate portion

In some embodiments, the scribe-line region is disposed adjacent to thenon-scribe-line region.

In some embodiments, the first substrate portion and the secondsubstrate portion each contain silicon.

In some embodiments, the second substrate portion is thinner than thefirst substrate portion.

In some embodiments, the first substrate portion has a first thicknessless than about 3 microns; and the second substrate portion has a secondthickness less than about 4000 Angstroms.

In some embodiments, the first substrate portion is in direct physicalcontact with the second substrate portion.

In some embodiments, the image sensor device further comprises: anorganic portion disposed in the scribe-line region and over the secondsubstrate portion.

In some embodiments, the image sensor device further comprises: aninterconnect structure disposed over a front side of the first substrateportion and the second substrate portion; and an anti-reflective layerdisposed over a back side of the first substrate portion and the secondsubstrate portion.

Another one of the broader forms of the present disclosure involves animage sensor device that includes: a radiation-sensing region located ina silicon substrate, the radiation-sensing region being operable tosense radiation projected from a back side of the silicon substrate; asilicon component located adjacent to the silicon substrate; an organiccomponent located over a back side of the silicon component; and aninterconnect structure located over a front side of the siliconsubstrate and a front side of the silicon component; wherein: theradiation-sensing region is located in a pixel region of the imagesensor device; and the silicon component and the organic component arelocated in a scribe-line region of the image sensor device.

In some embodiments, the image sensor device of further comprises: ananti-reflective coating (ARC) layer located over the back side of thesilicon substrate, wherein the silicon substrate is separated from theorganic component by a portion of the ARC layer.

In some embodiments, the silicon component is at least partiallyseparated from the organic component by another portion of the ARClayer.

In some embodiments, the silicon substrate is contiguous with thesilicon component.

In some embodiments, the interconnect structure includes one or morebonding pads.

In some embodiments, the silicon component is substantially thinner thanthe silicon substrate.

Still another of the broader forms of the present disclosure involves amethod of fabricating an image sensor device, the method includes:forming a plurality of radiation-sensing regions in a substrate, theradiation-sensing regions being formed in a non-scribe-line region ofthe image sensor device; forming an opening in a scribe-line region ofthe image sensor device by etching the substrate in the scribe-lineregion, wherein a portion of the substrate remains in the scribe-lineregion after the etching; and filling the opening with an organicmaterial.

In some embodiments, the portion of the substrate in the scribe-lineregion is in direct physical contact with the substrate in thenon-scribe line region.

In some embodiments, the portion of the substrate in the scribe-lineregion is thinner than the substrate in the non-scribe line region.

In some embodiments, the method further comprises: forming a colorfilter layer over the non-scribe-line region of the substrate, whereinthe color filter layer and the organic material have the same materialcompositions.

In some embodiments, the radiation-sensing regions are formed from afront side of the substrate; and the method further comprises, beforethe forming the opening and after the forming the radiation-sensingregions: forming an interconnect structure over the front side of thesubstrate; bonding the substrate to a carrier substrate, theinterconnect structure being bonded between the substrate and thecarrier substrate; and thinning the substrate from a back side, the backside being opposite from the front side.

In some embodiments, the method further comprises, after the filling theopening: performing an etching process to the organic material to exposea bonding pad of the interconnect structure.

The foregoing has outlined features of several embodiments so that thoseskilled in the art may better understand the detailed description thatfollows. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method of fabricating a semiconductor imagesensor device, comprising: forming a plurality of radiation-sensingelements in a first region of a substrate; partially removing thesubstrate in a second region that is different from the first region,wherein after the partially removing, a remaining portion of thesubstrate in the second region is substantially thinner than thesubstrate in the first region; and selectively etching away segments ofthe remaining portion of the substrate in the second region.
 2. Themethod of claim 1, wherein: the first region is a pixel region of thesubstrate; and the second region is a scribe-line region of thesubstrate.
 3. The method of claim 1, wherein: the remaining portion ofthe substrate in the second region is less than about 4000 angstromsthick; and the substrate in the first region is less than about 3microns thick.
 4. The method of claim 1, wherein the partially removingof the substrate is performed in a manner such that the remainingportion of the substrate in the second region is in physical contactwith the first region of the substrate.
 5. The method of claim 1,further comprising: after the selectively etching away, forming anorganic material to replace portions of the substrate that have beenremoved in the second region.
 6. The method of claim 5, furthercomprising: performing a dicing process in the second region of thesubstrate, wherein the dicing process is performed through the organicmaterial and through the remaining portion of the substrate in thesecond region.
 7. The method of claim 5, further comprising: before theforming of the organic material, forming an anti-reflective coating(ARC) layer over the substrate in the first region and the secondregion.
 8. The method of claim 1, wherein the substrate includes a firstside and a second side, and wherein the method further comprises, beforethe partially removing of the substrate in the second region: forming aninterconnect structure over the first side of the substrate; bonding thesubstrate to a carrier, such that the interconnect structure is disposedbetween the carrier and the substrate; and thinning the substrate fromthe second side.
 9. The method of claim 1, wherein: the interconnectstructure includes one or more bonding pads; and the selectively etchingaway of the segments of the remaining portion of the substrate comprisesetching away portions of the interconnect structure until the one ormore bonding pads are exposed.
 10. A method of fabricating asemiconductor image sensor device, comprising: forming a plurality ofpixels in a pixel region of a substrate, wherein the substrate furthercontains a scribe-line region that is different from the pixel region;performing a first etching process in the scribe-line region to form arecess in the second region, wherein the first etching process isperformed such that a layer of the substrate remains in the secondregion after the etching, the layer of the substrate having apredetermined thickness and being exposed by the recess; and performinga second etching process in the scribe-line region that selectivelyremoves portions of the layer of the substrate in the scribe-lineregion.
 11. The method of claim 10, wherein: the predetermined thicknessis less than about 4000 angstroms; and the pixel region of the substrateis less than about 3 microns thick.
 12. The method of claim 10, whereinthe first etching process is performed in a manner such that the layerof the substrate in the scribe-line region remains contiguous with thepixel region of the substrate after the recess has been formed.
 13. Themethod of claim 10, further comprising: after the second etching processhas been performed, filling the recess with an organic material; andthereafter performing a dicing process in the scribe-line region of thesubstrate.
 14. The method of claim 10, wherein the substrate includes afront side and a back side, and wherein the method further comprises,before first etching process is performed: forming an interconnectstructure over the front side of the substrate, wherein the interconnectstructure includes one or more bonding pads; bonding the front side ofthe substrate to a carrier, wherein the interconnect structure islocated between the carrier and the substrate after the bonding; andthinning the substrate from the back side; wherein the performing of thesecond etching process includes etching portions of the layer of thesubstrate and portions of the interconnect structure over the one ormore bonding pads until the one or more bonding pads are exposed.
 15. Amethod of fabricating a semiconductor image sensor device, comprising:forming a plurality of radiation-sensing regions in a substrate, theradiation-sensing regions being formed in a non-scribe-line region ofthe image sensor device; forming an opening in a scribe-line region ofthe image sensor device by etching the substrate in the scribe-lineregion, wherein a portion of the substrate remains in the scribe-lineregion after the etching; and filling the opening with an organicmaterial.
 16. The method of claim 15, wherein the portion of thesubstrate in the scribe-line region is in direct physical contact withthe substrate in the non-scribe line region.
 17. The method of claim 15,wherein the portion of the substrate in the scribe-line region isthinner than the substrate in the non-scribe line region.
 18. The methodof claim 15, further comprising: forming a color filter layer over thenon-scribe-line region of the substrate, wherein the color filter layerand the organic material have the same material compositions.
 19. Themethod of claim 15, wherein the radiation-sensing regions are formedfrom a front side of the substrate; and further comprising, before theforming the opening and after the forming the radiation-sensing regions:forming an interconnect structure over the front side of the substrate;bonding the substrate to a carrier substrate, the interconnect structurebeing bonded between the substrate and the carrier substrate; andthinning the substrate from a back side, the back side being oppositefrom the front side.
 20. The method of claim 19, further comprising,after the filling the opening: performing an etching process to theorganic material to expose a bonding pad of the interconnect structure.